This invention relates to a device for visually checking the degree of clogging of an air filter in motor vehicle engines.
The internal combustion engines of motor vehicles and the like require the intake of a considerable quantity of air for their operation, this being necessary for the combustion process.
However, atmospheric air contains a large quantity of solid particulate of various kinds, which if drawn in together with the air can cause serious damage to the engine.
These engines are therefore provided at the combustion air inlet mouth with a filter able to retain a large part of the solid particulate without substantially hindering air passage, because of its large filtering surface.
However, with the passage of time these filters are subject to progressive clogging due to the deposition of filtered material on their surface, and therefore after a certain period of use offer a resistance to air passage which is no longer negligible. The result of this is an unbalance in the engine feed, with consequent non-optimum engine operation.
This clogging cannot be currently measured reliably, it being determined either by an approximate visual evaluation of the filter after removing it from its housing, or by a fixed period of filter use, but which does not take account of the variable engine utilization conditions and the consequent different degree of filter clogging.
The problem therefore arises of providing a device for checking the degree of clogging of the filter which allows reliable monitoring of the filter efficiency without having to remove it from its seat.